<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <script type="text/javascript">
        var m = '3';
        var n = 3;
        if (m == n) {//值相等就可以
            console.log('m==n');
        }
        if (m === n) {//值相等，类型也要相等
            console.log('m===n');
        }
    </script>
</body>
</html>